Fortunately, one of the Websleuths verified attorneys exchanged some messages with us about this case. They explained the strategies prosecutors use to set up and negotiate plea deals successfully and how the process works. We had this discussion here back when it looked like AW's mom, Rita N, was going to make a plea deal.
Once RN made her deal, things were looking grim for the rest of the 4 Wagners. As the evidence piled up, the taped conversations AW had with her mom and brother were added. One can only imagine there was damning evidence in those hours of phone conversations.
According to
@PrairieWind's tutorial, scheduling Jake's trial first was an important move.
Exposing all the evidence in the strongest case at trial would put pressure on the rest of the defendants to bargain. That also meant Jake would likely be found guilty and sentenced to death. He had to make the first deal in order to save his own life.
The fact the defense teams submitted zero evidence to exonerate their clients, then announced they would challenge the scientific validity of ballistic and shoe print evidence was another bad omen. By the time they got around to Agent Scheiderer's testimony at GW4's hearing and the "Other Acts" evidence, the outlook was grim. The "Other Acts" painted a horrifying picture of the Wagner family and their history of abusive, twisted behavior.
The only part of Jake's plea deal that surprised me was that he capitulated so quickly. His trial wasn't scheduled until August 2021.
ETA: Our WS verified attorney member had nothing to do with the 4 Wagners' cases nor had any inside information. They simply read what was linked to here at WS and gave us a textbook description of why, how and when plea bargains are negotiated and managed by prosecution and the court in murder cases.